BioShock "surprise announcement" this Sunday

Downloadable plasmids?

There's only two weeks until its 360/PC release but apparently we don't quite know everything there is to know about BioShock.

According to our friends at Kotaku, Irrational Games is set to make a surprise BioShock announcement on TV this weekend, alongside a brand new trailer. "You won't want to miss this!" TV show Game Head promises.

A reliable source tellsus that the announcement will involve Xbox 360 download content - specifically downloadable plasmids for the console version. We'll let you know how good our info is on Sunday.